Toners of three colors that are cyan, magenta, and yellow are used to form a full-color image, and a black toner may be used in addition to these toners. Generally, since such a full-color image is preferably formed by use of toners which are identical in material other than a coloring agent, there is an idea of a full-color toner set.
For example, Patent Literature 1 discloses a full-color toner set such that toners of cyan, magenta, and yellow each contain polyester resin as a binder resin, a coloring agent, and a grinding aid, and a copolymer resin containing a styrene monomer and an indene monomer is used as the grinding aid. Patent Literature 2 also discloses that the grinding aid is contained in an amount of 1 part by weight to 20 parts by weight, and more preferably of 3 parts by weight to 15 parts by weight, with respect to 100 parts by weight of the binder resin. According to the full-color toner set of Patent Literature 1, the toners of the respective colors can be made identical in grindability.